module.field_spec (FieldDef[]: key/label/type/options/required) declares a
module's own operational fields, validated on create/update. client_module
gains field_values (JSON map of non-secret values, type-checked against the
owning module's spec) + secrets_enc (one AES-GCM blob over a {key:plaintext}
map; the clear key-list prefix lets the UI show which secrets are set without
decrypting). Routes: PUT /client-modules/:id/fields (staff), POST
/client-modules/:id/secrets + /reveal-secret (managerial, audited, plaintext
never logged). Additive over D20 — provider/username/password stay. Both
engines (SCHEMA + migrate guards + pg 003). 11 new tests; module suite green.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>